Bill Carey was slurring his words, the left side of his face was drooping, and he could barely lift his left arm or leg by the time he was wheeled into a surgical suite at UCSF.

Unfocused and confused, he was hardly aware that he was having a stroke. He didn't realize how serious his condition was, and that there was no telling what kind of damage he'd face when he woke up from the procedure he was about to undergo.

A team of doctors specialized in radiology and neurosurgery took just over half an hour to thread a catheter from a blood vessel in Carey's leg all the way to his brain, and pluck a clot from one of the major arteries there.

When Carey woke up an hour or two later, he was fine - no slurred words, no weakness.

Right before the surgery, a doctor told Carey about a "new tool we can use to get that thing out of your head," said the 69-year-old Pacifica man, who had his stroke two years ago.

"I said, 'Where do I sign?' " Carey said. "The next thing I remember, I was fully awake and alert in the neurological intensive care unit."

Clot-busting drugs

Doctors increasingly are relying on clot-removing technology like the vascular device they used in Carey's case to treat stroke victims who don't respond to the usual emergency clot-busting therapy.

That therapy - a drug called tissue plasminogen activator, or tPA, that attacks and breaks up clots - was revolutionary for stroke treatment when it was approved in the mid-1990s. It was the first, and for a long time only, treatment for strokes caused by blood clots.

But tPA has limitations. It must be given within 4 1/2 after the onset of stroke, or else the risk of side effects like excessive bleeding becomes too high, and it's thought that the damage done by lack of blood flow to the brain may be irreversible after that much time. Plus, tPA doesn't always work on large clots that are tougher to break up.

Shortly after tPA was approved, doctors began experimenting with injecting the drug straight into the larger clots to see if that helped destroy them. Results were mixed - some patients clearly benefited but others didn't, and clinical trials were inconclusive.

Grasping at clots

Meanwhile, other doctors got more creative in going after the clots. In the mid-2000s, they began using devices, similar to the one UCSF doctors used to treat Carey, to grab clots and pull them out of the brain.

"We can truly begin to save lives with these devices and turn their neurological function to normal," said Dr. Wade Smith, chief of stroke neurology at UCSF. "That's the holy grail we're looking for."

The first device was a tiny corkscrew attached to the end of a guide-wire. To use it, doctors had to weave a catheter through the blood vessels into the brain until they reached the clot, then guide the corkscrew into the clot.

The corkscrew device, which is still in use, was developed not for clot removal, but to retrieve foreign items that had been left behind after endovascular surgery, such as pieces of catheters or stents that can cause long-term problems for patients. It works on blood clots too, but that wasn't what it was designed for so doctors hoped to improve it.

Improving the technology

Over the past decade, other scientists have been trying to hone clot retrieval technology. The current most popular devices are like cages that, instead of surrounding a clot, are inserted into the middle of it and expanded. The clot becomes stuck in the cage material, allowing doctors to pull it out. Other devices use vacuum technology to suck out clots.

One of the first doctors to use the corkscrew device was Dr. Christopher Dowd, a UCSF neuro-radiologist, on a 16-year-old girl in 2004. He also treated Carey, using one of the cage devices that only became available two years ago.

"It takes a minute or two to tug the clot out gently and pull it onto the sheet. If there's a big fish on the line, everybody whoops and hollers," Dowd said. Most of the clots are about half an inch wide, although he's removed larger ones.

The clot retrievers can be life-altering or even life-saving for certain stroke patients - the tough part is determining which patients will benefit.

Weighing risk and benefit

A study released last year drew widespread attention among stroke experts when it reported that the clot retrievers, on the whole, didn't offer benefits to patients in terms of their recovery. The study showed that the retrievers were often successful at removing clots, but that it wasn't clear how many patients' conditions were improved by the treatment.

Clot retrievers aren't without risk. Like any surgical procedure, patients can get infections or experience pain or discomfort, or more seriously - but very rarely - the device can damage blood vessels or even lead to another stroke. Plus, it's expensive.

If a person's brain is already too damaged by a stroke to benefit from clot removal, there's no need to put that patient through the cost and risk of the procedure, stroke experts say.

That's why more work needs to be done to identify the right patients.

Time to save a brain

Doctors have long decided who to treat with tPA based entirely on the length of time since their stroke began. Many specialists still consider time to be the most important qualifier for clot retrievers too.

But there are other factors to consider, say neuro-radiologists, who specialize in using imaging equipment to define what's happening in the brain during and after a stroke. Scans may show that despite a major clot, smaller, unblocked vessels are still supplying blood to the affected part of the brain, preserving the tissue there and expanding the window of time for treatment.

Dr. Huy Do, an interventional neuro-radiologist at Stanford, said making decisions based only on a time window isn't good enough. He recalled two recent patients - one, a young man who came in for treatment only an hour after suffering a stroke, and the second, a woman in her 80s who was seen six hours after her stroke.

The young man, brain images showed, had suffered such sudden and extreme damage that clot retrieval wouldn't help him. Imaging on the woman, however, showed that most of her brain was still being supplied with blood and there was still time to treat her.

"Before, we were just going by a time window," Do said. "Now with more knowledge, especially with imaging, we find every patient is individual."

More research needed

Dowd, Do and other stroke experts are pushing for more clinical trials to identify the subset of patients who, like Carey, will clearly benefit from clot retrievers. Just a decade ago, those patients would have died or become permanently disabled by their stroke when the drugs didn't work.

With a clot retriever, they could have a dramatically different outcome.

"In the old days, and I've been at UCSF for 28 years now, when someone came in with an acute stroke you'd put them on a gurney in the back corridor because that's all you could do," Dowd said. "Now it's like a heart attack, there are things we can do. Now it's all hands on deck for a stroke."

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